The most important rule when hoarding goods is simple: buy cheap and sell high.

It’s an obvious principle that even a first-grader would understand, but actually putting it into practice is incredibly difficult.

It’s like saying, “If you study hard, you can get into Seoul National University.”

‘Both making money through hoarding and getting into Seoul National are hard.’

Hoarding for profit often goes wrong with just a slight misstep in timing, forcing you to sell stockpiled goods at half price—or worse, a third of the cost.

But just as you can’t catch a tiger without entering its den, to …